Piston.



R. ALLEN.

PIsToN.

LLLLLLLLLLLLLLLLLLLL 13. 1908. 920,237'. Patented May 4, 1909.

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B.. ALLEN.

PISTON.

APPLICATION FILED JULY 13, 1908.

PatentedMay 4, 1909.

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R. ALLEN.

PISTON.

APPLICATION FILED JULY13, 1908.

Patented May 4, 1909.

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- PISTON.

APPLIoATIoN FILED JULY 1a, 190s.

920,237. Patented 4, 1909.

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PISTON.

APPLICATION FILED JULY 13| 190B.

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ROBERT ALLEN, OF CAVlllSllh, llh'GliAh'l).

To all whom it may conce/ra:

Be it known that l, ltonn'r ALLEN, a subject of the King of Great Britain and lreland, residing at Oakdene, Kidmei'e Road, Cavershan'i, Oxfordshire, England, have invented certain new and useful Improvements in Pistons, of which the following is a specification.

My invention relates to pistons of the type having metallic packing rings formed in two or more parts or segments which are forced outward or expanded against the cylinder by radial chokes, gluts or wedge blocks which choke the joints between the contiguous ends of the segmental packing members. As heretofore constructed such packing consisted of a ring of square or rectangular section which although very ellicient in many respects was incapable of fulfilling all requirements of a perfect piston packing under the varying conditions of working, inasmuch as no effective provision was made for eounteracting steam pressure on the perimeter of the ring, the expanding wedges or eliokes being only intended to exert su'llicient outward pressure on the rings to insure a tight packing against the cylinder wall under normal conditions of working. Further the rings were liable to become steam packed through steam passing down the side of the packing ring groove in the piston head and underneath the ring.

The object of my invention is to prevent the packing rings from being forced inward by steam or other pressure acting thereon in the opposite direction to their expanding wedges or eliokes, as for instance when the rings are used on piston valves and become exposed to the steam on their peripheral surfaces when passing over ports, also at the same time to maintain the ring tightly pressed against that side of the groove nearest the pressure side of the piston, or against both sides where required and to interpose an effectual barrier at the joint which shall not uncover by wear.

My invention provides an efficient packing for the pistons of steam engines, internal combustion engines, or compressors being equally effective whether working with steam, gases, air or liquids.

In the accompanying drawings Figure l is a sectional end elevation of a piston constructed according to this invention, the upper half section being taken along the line PISTON.

Patented May 4, 1909.

Serial No. 443,321.

G. H. and the lower half along the line l. J. Fig. 2. Fig. 2 is a sectional side elevation of the piston, Figs. 3 to 5 are elevations at right angles and plan respectively of a choke or wedge piece for expanding the packing ring, Figs. (5 to S are similar views to Figs. 3 to 5 of a choke or wedge l'or expanding the compleniental wedging or packing ring: Fig. 9 is a transverse section of the packing, Fig. l() is a sectional end elevation of part of a piston showing a slightly modified form oll packing; Figs. 1l and l2 are transverse sections through the piston taken respectively at l --x and f z/-fg/ Fig. l0; Figs. l0 and .l 1.*l are similar views to Figs. l0 and l] showing the application of the improved packing to the piston of an internal combustion engine. Figs. 13 to l5 are elevations at right angles and plan respectively of the choke or wedge employed to expand one half of the j'iacking and Figs. 16 to 1S are similar views olI the wedge for expanding the other or complemental half of the. packing.

in a practical form of my invention as applied to packing rings ol' piston valves, shown in Figs. l to 9 which valves would usually be double ended, one of the side faces of each segment or half a forming the ring is beveled or inclined from the outer edge inward and under-cut to forni a space l) for the reception of a complementa-l wcdging and kicking ring a which replaces the cut away portion of the packing ring a and fills the groove c, with the exception olI a small space c which is left be tween the rings 1. (l/ to allow adjusting for wear Fig. t).

Both the packing ring a and its coinplemental wedgiiig and locking ring a are formed in two or more parts or segments and expanded by wedges or eliokes d interposed between the ends of the segments. As shown each ring is divided into three segments, the wedges d of one packing ring being disposed intermediate the wedges ofthe adjacent ring, as illustrated in Fig. 1. '.lhe wedges (Z are eut away at d (Z2 and otherwise shaped to conform to the sections of the segments on which they act and are formed with hollow stems c which are inserted in radial pockets]` in the piston head, and are pressed outward by helical springs g located in the hollow stems e, or the springs may be applied to the eliokes in any other suitable manner. The stems e of the wedges are cylindrical and a segment e forming a continuation of the llt) stern e extends up to the top of the Wedge d, j and insures a thorough closure at the joint. j

It Will be seen that the packing ring a and its locking ring a have a Wedging action one upon the other Which keeps the packing ring tightly pressed against the side of the groove c in the piston head. This Wedging action however does not prevent the ring from expanding; but by forming the beveled or Wedging surfaces a2 so that they make a sufficiently slight angle vvith the side faces a3 of the rings, the reaction between the Wedging surfaces a2 is arranged to bear such a relation to the pressure at the side faces a3 of the ring that the packing ring a is automatically locked by the Wedge ring a and prevented from being pressed inward by the steam pressure vfhen the outer face of the ring is exposed to such pressure when passing over ports or the like. It vvill be seen that the exposed outer edge of the wedge ring is made as thin as possible so that there is practically no inward pressure exerted by the steam on the edge of this ring.

N'Vhere the packing rings are not liable to be exposed to the direct pressure of fluids on their outer faces the inclination of the Wedging surfa es between the two co-acting rings is only required to be such that the main ring is kept up against the adjacent side of its groove irrespective of the direction in which the piston is traveling. Thus the vredge ring may take a very simple form. A packing of this type is shown in Figs. 10 to 1S. The two sets of ring segments a a have co-acting wedge surfaces a2, and are expanded by Wedges d shaped to conform to the section of their respective packing ring segments.

In internal combustion engines wherein considerable heajng of the piston occurs, l preferably arrange the pockets f for the expanding Wedges Z in such a manner that air can circulate freely around the pockets as shomi in Figs. l0'UL and 1la and exercise a cooling action thereon.

emu,

That claim, and desire to secure by Letters-Patent is l. A piston packing comprising a segmental packing ring seated in the groove of the piston, a segmental Wedging and locking ring, said ring having cooperating inclined meeting edges adapted to force the side edges of the packing laterally against the Walls of the piston groove when acted upon by external pressure, and a series of spring pressed Wedges to 'expand the packing rings radially against the cylinder.

2. in combination with a piston provided `with an annuiargroove and a series of radially and inward` extending pockets at the inner vrarllofgits roove, a packing comprising segmental Wedging or locking rings seated in the groove, and a series of exianding Wedges for expanding the packing sections radially, said Wedges having hollow stems to seat in the pockets of the piston, and coil springs arranged in the stems of the Wedges with their inner ends seating in the pockets.

3. In combination Witha piston provided with an am lar groove and a series of radially and ir vardly extending pockets at the inner Wall oli-its gi 4ove, a packing comprising segmental vedg g or locking rings seated in the groove, a series of expanded. Wedges for expanding the packing sections radially, said Wedges having hollow stems to seat in the pockets of the piston, and coil springs arranged in the stems of the Wedges 1with their inner ends seating in the pockets, each of the Wedges having a Wedge shaped portion extending to the outer edge of the packing and forming a section thereof and Which provides a closure at the joints of the packing ring sections.

in testimony whereof have aflixed my signature, in presence of two Witnesses.

HUBERT ALLEN.

Vvlitnesses:

H. D. JAMIsoN, A. NUTTING. 

